the current situation of gi and ga applications ... 20110721.pdf · the current situation of gi and...

Zinc…essential for life

The Current Situation of GI and GA

Applications

Construction

Automotive

Panels processed to have a weathered appearance for exposed architectural uses (left to right: weathering

steel, verdigris copper, weathered galvanize) also have better values for SRI (solar reflectance index), SR (solar

reflectance) and TE (thermal emittance).

Cool Roofs

Goodwin & Silva Galvatech 2011


Where low relectivity and emissivity is desired: solar-thermal houses in

Lausanne

Imlau, Galvatech 2011

Compost House Frame for Fish Farm

Greenhouse Indoor Baseball Field

Sound Barrier in Station Building Ventilation Duct in Train Depot

Trackside Cable Tray Cable Bracket

Sound barrier (front) Sound barrier (back)

Fireproof Duct for Optical Cable Wind Barrier Panels

Air Conditioning Unit Power Control Cabinet

Photovoltaic Panel Frames

Fuel Tank for Oil Heater

Corrugated Roof

Air Conditioner Trestle

Self Propelled Multistory Parking Garage Deck Plate for Parking Garage

Parking PalletSmall Parking Structure

Corrosion testing of TKS ZM1 (1%Al, 1%Mg)

Observed corrosion mechanisms of Zn and ZM1 coil coated sheets

ZM1 130G275

Profilesafter SST

Schulz, Galvatech 2011

SKP evaluation of paint delamination on ZM1 150 and G275

polyesterprimer 5 μm, no chemical pre-treatment, 0.5 % NaCl-solution, SKPresolution of 50 μm in X and Y direction, RH 95% at 20 °C


Paint delamination and corrosion at cut edges, scratches and on 4-T bending shoulder of Z275, ZA255 and ZM130 2000 hours SST (DIN EN ISO 9227), each with polyester

coating (25 μm) and chromium(VI)-free pretreatment


Comparison of corrosion at cut edges after DIN EN ISO 9227 SST of ZM1 130, AZ 185, ZA 255 and Z 275 without polyester coating (test duration 385h) and with polyester coating (SP25, 25 μm, test duration 1000 h)


Paint delamination from scribe of Zn-2%Al-2%Mg coating and different GI coatings after 10 weeks

VDA 621-415 CCT

Luckeneder, Galvatech 2011

Cr+6-free and Cr-free treatments

APGalva09 C-11

Permanent coatings: Short drying periods and consequently resistance against mechanical wear at the

application stage. Transparent, excellent resistance against weathering

APGalva09 C-11

APGalva09 C-11

Weldable Organic Coatings

APGalva09 C-11

Inorganic Passivation

APGalva09 C-11

Chrome in coil pre-treatment processes had been progressive: i. Alkaline conversion (Co or Ni based) in combination with Cr-free post rinse (Zr based). Still used in some European lines for outdoor exposed materials coated with Cr-free primers ii. Co-based conditioner in the second cleaning bath (if available) and Cr-free pre-treatment applied by chem.-coater. Several line trials have shown similar results to Cr iii. Cr-free no-rinse products applied by a chem.-coater. They are based on Titanium Fluoride, Phosphoric acid and organic polymers. Heavy metal-free systems based on Silane compounds are now available. The experience has shown that Chrome-free coil coating systems are able to provide similar corrosion protection as compared to Chrome containing systems. On the other hand, the results indicate that in case of Cr-free processes the primer has a more significant impact on the final product performance than for Cr containing pre-treatment systems.

History of Hexavalent Cr Replacements in the Coil Coating Process

APGalva09 C-11

Hexavalent Cr Replacements in the Coil Coating Process

APGalva09 C-11


Typical North America and Japan trends reached the 80% level 10 years earlier


North American Light Vehicle Aluminum Content

- History and Forecast -


North American Light Vehicle Trend for Flat Rolled UHSS and AHSS

(Net Pounds per Vehicle)


NA Light Vehicle Growth Forecast for Flat Rolled Advanced and Ultra High Strength Steels

2009 – 2020 (net pounds per vehicle)

A. Abraham, GDIS 2011

Regional Differences in Automotive Coatings

Coated automotive tonnage in North America is about 70% Zn-Fe [galvanneal (GA) and electrodeposited 15%Fe-Zn alloy (EGA)]-coated

Europe: about 85% of the automotive tonnage is GI coated, the opposite of the GA-GI ratio in eastern Asia.

China: GA-GI ratio is more similar to that of NA.

GA is the most widely used critical exposed(CE) coating in NA, followed by Zn EG then EGA, with GI the least used CE coating, a very different trend than in Europe.


New Vehicle Applications of GI/GA

North America 2011 Chevrolet Volt2011 Ford Explorer2011 Jeep Grand Cherokee

Korea: Hyundai-Kia

GDIS 2011

Expected trend at Hyundai-Kia

Hyundai-Kia Outer Panel Trend

Hot Press Forming of Galvanized AHSS

I.R. Sohn, SCT 2011

Cross section and EDS analyses of conventional Zn coated sheet press formed after heating to

910℃ for 5 min.

I.R. Sohn, SCT 2011

Cracks propagation through grain boundaries on a HPF component

I.R. Sohn, SCT 2011

Cross section of newly developed POSCO Zn coated 22MnB5 1500 MPa grade, press formedafter heating to 910℃ for 5 min. with ZnO-Al2O3

surface layer

I.R. Sohn, SCT 2011

Cross sections of the most severely deformed portions in U-channel hot stamping:

(a) Developed POSCO Zn HPF steel, (b) Conventional GI steel, (c) AlSi coated HPF steel

a b c

I.R. Sohn, SCT 2011

Corrosion blisters on ELPO coated panel after 480h(SST) (a) conventional GA (b) conventional GI steel, (c)

Developed POSCO Zn HPF steel after HPF at 900℃ for

5min.

I.R. Sohn, SCT 2011

TKS GammaProtect Zn-Ni EG

As-coated EG coating depth profile Corresponding X-ray diffraction pattern showing Υ-Ni5Zn21 phase

J. Kondratiuk, Galvatech 2011

SEM cross-section image of Zn-Ni coating after 300s of heat treatment at 880°C and phase

distributions after different soaking times

300s

420s 600sJ. Kondratiuk, Galvatech 2011

Cross section through TKS MBW® 1500 + GammaProtect® after 144 h SST

M. Köyer, SCT 2011,

Indirectly hot stamped 22MnB5 B-pillars using GammaProtect

J. Kondratiuk, Galvatech 2011

Galvanizing of Different Kinds of Steel

Construction: Full HardAutomotive: DP, TRIP, UHSS, hot rolled HSS and cold rolled

Production of Full Hard Grades for Construction Applications

ASTM A109

• Full Hard UTS 620 + 70 MPa, no elongation requirement

Alloying Approaches to Increase Full Hard Window

ILZRO ZCO-1-2

Reduction of Oxides and Furnace Gas Dewpoints

Overview of Hardening Mechanisms in Automotive Steels

Steel Grade Alloy Basis Hardening Mechanism Main Alloying Addition

Microalloyed grades LC

Precipitation,

grain refinement,

solid solution

Ti, Nb and/or V

Mn

Rephosphorized LC grades

LCSolid solution,

grain refinement

P, Mn, Si

HS IF grades IF (Ti, Nb or Ti + Nb)

Solid solution,

grain refinement,

precipitation

P, Mn, Si, B

BH grades (LC) LC

Solid solution,

grain refinement

P, Mn, Si

BH grades (ULC) ULC (Ti, Nb, V)

Solid solution,

grain refinement

P, Mn

DP/MP grades LC Transformation C, Mn, Cr, Mo

TRIP grades LC Transformation C, Mn, Si, Al, P

AHSS — Types and Description

Typical applicationsCrush structures: Rails, pillarsDent resistance: Exposed Body panels

Dual Phase (DP) O.1C-Mn-Si/Aℓ Ferrite-Martensite structure 500 – 1000 MPa Tensile Strengths

High work hardening

High elongation Good TS – Elongation — Energy absorption High bake hardening

Manufacturability

AHSS — Types and Description (continued)

Typical applicationsCrush structures: Rails, pillars

TRansformation Induced Plasticity (TRIP) steels

O.15C-Mn-Si/Aℓ (Mo) 500 – 1000 MPa Tensile Strengths

About 4 – 12% retained austenite

Deformation transforms the austenite • high work hardening• high energy absorption

Welding issues

Continuous Annealing for AHSS

Transformation Strengthening

Principle: Transform to complex (multiple)phases; bainite, martensite and retained austenite

Keys: • Composition control to produce required phases with a given CAcycle

• Low alloy steels (C, Mn, Si, Mo, etc.)

• Intercritical annealing to provideΥ + starting structure with

high C

Continuous Annealing for AHSS

Benefits of Transformation Strengthening

Unique structures

Unique properties—high TS—low Yield/Tensile ratio—high work hardening—better ductility at

a given TS

Automotive application—crash enhancement—weight reduction

Typical GI/GA Temperature Cycle(ref APGalva’09 A45)

Studied Steels and GA Temperatures (ref APGalva’09 A45)

Schematic diagram of the oxidation kinetics mechanism of high strength steel

Appearance of GA coatings on (a)-(c) 1180CP(d)-(f)590TRIP (g)-(i) 1180TRIP(ref APGalva’09 A45)

Coating weights and coating compositions of GA panels and surface compositions of annealed

substrates (ref APGalva’09 A45)

Surface morphology of GA coatings on various steels(a)-(c) 1180CP, (d)-(f) 590TRIP and (g)-(i) 1180TRIP

XRD patterns of GA coatings on various steels (a) 1180CP, (b) 590TRIP, and (c)

1180TRIP (ref APGalva’09 A45)

Surface morphology of GA coatings in selected areas on (a) 1180TRIP-0 (2000X), (b) 1180TRIP-0 (4000X), and (c) 1180TRIP-35 (4000X) (ref APGalva’09 A45)

Cross-sections of GA coatings on various steels(a)-(c)EDDQ

(d)-(f)1180CP

(g)-(i) 590TRIP

(j)-(l) 1180TRIP

Cross-sections of as-hot-dipped (AHD) coatings on

(a)-(c) EDDQ

(d)-(f) 1180CP

(g)-(i) 590TRIP

(j)-(l)

1180TRIP

Processing of DP980 GA (APGalva’09 ref B13)

Results with CR=40%, ST=810℃ , GA=490 ℃

Heat Cycle for DP Steels(APGalva’09 ref B13)

Effect of Annealing T on Mechanical Properties (APGalva’09 ref B13)

SEM images according to annealing temperature: (a) 750℃, (b) 790℃, (c) 830℃(APGalva’09 ref B13)

Effects of galvannealing T on mechanical properties (APGalva’09 ref B13)

SEM images according to galvannealing temperature: (a) 460℃,

(b) 500℃ (APGalva’09 ref B13)

Results with ST=810℃ , GA=490 ℃,

CW=45 g/m2 per side(a) surface appearance (b) cross section

Result of bare spot analysis

GA coating in (a) Si-TRIP and (b) Al-TRIP steel

(a) (b)

Bhattacharya, Galvatech 2011

Hot rolled galvanizing and its end applications

Two basic families of advanced hot rolled steels:

-precipitation strengthened-multiphase (TRIP, ferrite-bainite, etc)

Grades we have studied in the GAP program

Mechanical Properties of PrecipitationStrengthened Hot Rolled Steels

• Precipitation-strengthened hot rolled steels with 0.5-1.4% Mn and up to 0.14% Si can be galvanized to produce good quality coatings.

• The best results were obtained by reheating to 550 or 600°C in a 20%H2-N2 atmosphere with a -30°C dew

point.

• Under these conditions, the coatings contained 0.006% (Steel A), 0.124% (Steel C) or 0.057% (Steel D) total bare area.

Mechanical Properties of TRIP Hot Rolled Steel

For the hot rolled C-Mn-Si TRIP steel, the best coatings were obtained using a 20%H2-N2atmosphere with -30°C dew point, overaging at 470°C and zinc bath temperature of 460°C. The percent bare area obtained using these galvanizing conditions was 0.130%, which is similar to the coating quality obtained on the precipitation-strengthened Steel C.

Hot Rolled Steels Chosen for Study at voestalpine

These are processed to give a ferrite/bainitematrix containing C-rich phases (martensite, retained austenite, bainite, pearlite). Stretch flangeability improved by minimizing hardness differences between phases and using fine grain microstructure

M. Sonnleitner, SCT 2011

Galvanizing Cycle for Hot Rolled Steels


Peak temperature was varied from <675°C to above Ae3

Effect of peak temperature during MULTIPAS® annealing cycles on yield stress, tensile

strength and elongation for heat A

Strip thickness = 2.5mm, coating thickness=120g/m2 (8.5µm per side) M. Sonnleitner, SCT 2011

Effect of peak temperature on YS and TS (heats A, B and D).


Results of hole expansion tests (60° conical punch, heat C, 2.5mm thickness)


Roll Forming Studies

Hat geometry (a), 180° center bending (b) and 180° side bending (c).


Results of profiles trials

Forming Limit Diagram


Typical roll forming applications in vehicle structures


Hot Rolled B pillar from TKS InCar project

B. Hammer, SCT 2011

Compared with reference material for B-pillars, DP-W® 600 as tailored blank, TPN®-W 900 enables a weight reduction of 3.48 kg per component and yields a cost reduction of 4.64 €.

Shimizu ,Beijing Forum 2010

Uranaka, Galvatech 2011

Auto parts made of ZAM Coated Steel

Motor Housings Cable clamps

Dust Covers Floor Brace


On-Vehicle tests for ZAM vs post-plated actual parts


Results of ZAM on-vehicle testing


Stone Chip Performance of ZAM

80 g/m² and Cr-free treatment

180 cycles of CCT Shimizu ,Beijing Forum 2010

Samples for JIS H 8502 CCT (2h SS, 4h drying at 60C, 2h 95%RH at 50C)


Surface Appearance of ZAM after CCT


Cross-sectional structures and surface morphologies of corrosion products formed on Zn-Al-Mg and post-Zn-coated material specimens after 40 cycles of CCT


Weight and appearance of phosphate film on ZAM, GI, GA

Result of paint adhesion testafter exposure to wetenvironment (ZAM30)

AGalva09 B-63

Maximum width of blister from cross scribed line of fully painted specimens subjected to 30 cycles of the Ford APGE corrosion test. (Bar range indicates the range of maximum width of blister among 3 specimens)

APGalva09 B-63

Average corrosion depth in evaluation area of each coupon subjected to perforation corrosion test (SAE J2334).

Bar range indicates the range of average corrosion depth among 3 coupons)

APGalva09 B-63

Appearance of evaluation area of each coupon subjected to perforation corrosion test (SAE J2334)

APGalva09 B-63

APGalva09 B-63

MagiZinc automotive testing – ELPO panels

Top row: details of about 2 cm of a scribe after 42 cycles in ECC1. Bottom: After 20 cycles of VDA621-415 CCT. The left top to bottom right scribe was aimed down to the zinc coating and the other scribe down to the steel substrate. The top of the panels were stone chipped and the top cut edge was unprotected

Vlot, Galvatech 2011

Results of Volvo CCT glass flange area observations of GI, GA, MagiZinc


Weight gain of the panel during the test Depth of steel attack in flange area after 18 weeks exposure

Adhesive Bonding Behavior

Resistance Spot Welding Behavior


the current situation of gi and ga applications ... 20110721.pdf · the current situation of gi and...

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